1. Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
2. Health Services Research Unit, University of Aberdeen, Aberdeen, UK
3. Health Economics Research Centre, University of Oxford, Oxford, UK
4. Department of Orthopaedic and Trauma Surgery, University of Dundee, Dundee, UK
5. Royal Bournemouth Hospital, Bournemouth, UK
6. Nuffield Department of Population Health, University of Oxford, Oxford, UK
7. Department of Primary Care and Population Health, University College London, London, UK